1. Field of the Invention
The present invention relates to an electromagnetic pickup for stringed musical instruments and, more particularly, to an electromagnetic pickup having alterable sound characteristics.
2. Description of the Prior Art
The present invention relates broadly to electrical musical instruments of the stringed type. It is particularly applicable to an electric guitar or a similar musical instrument having a plurality of stretched strings extending across a body and a neck in which the strings are caused to vibrate by plucking or picking them.
In order to derive an output from such an electric guitar or other similar electrical musical instrument, the instrument is conventionally provided with an electromagnetic pickup comprising a number of magnetic elements (pole pieces) having a conductive coil wound around them. Typically, one such pole piece is disposed directly beneath each string of the instrument. The strings are constructed of a magnetizable substance such as steel and therefore become part of the conductive path for the magnetic lines of flux of the pole pieces. Accordingly, when any of the strings are caused to vibrate, this causes a disturbance in the magnetic field of the associated pole pieces. This has the effect of generating a voltage in the conductive coil, which may be suitably amplified and transmitted to a loudspeaker system.
The typical string arrangement in which a pole piece is located directly beneath a string is shown in FIG. 1. This figure illustrates an electric bass guitar 10 including a pickup assembly 12 having four pole pieces 14a-d, with each pole piece being located directly beneath one of the strings of the guitar. This arrangement is typically referred to as a "percusive" pickup, since the resulting sound is a strong percusive sound followed by a very rapid decay or attenuation to a much lower sound level.
A second type of pickup is illustrated in FIG. 2. In this guitar, a pair of pole pieces 16 are provided for each string, with the string being located between the pole pieces. Alternatively, the pickup may be provided with one more pole piece than the number of strings and positioned such that each string lies between two adjacent pole pieces. Such an arrangement is disclosed in U.S. Pat. No. 2,968,204, issued on Jan. 17, 1961, to the same inventor as the present application. Such an arrangement is typcially referred to as a dual pole pickup. This type of pickup typically produces a sound which does not have an initial extreme percusive effect and which is more sustained.
It can be appreciated that in certain situations it is desirable to provide a percusive-type sound while in other instances it is desirable to provide a dual pole-type sound. In the past, this has required two different guitars, one each being provided with the desired pickup configuration.